The first value is the market value that varies with the demand and the supply that means according to the market forces.
The second part is the book value which is the intrinsic value of the security. It is the amount which is paid in order to obtain it.
A non marketable security is not exposed to the market forces hence its value never changes.
These are often specific types of Treasury bonds. U.S. savings bonds, government account series bonds are not traded in the market.
In general, Non-Marketable Securities cannot be bought or sold easily. This gives this investment a specific quality. That is why US Savings Bonds are considered to be one of the safest types of investments .There are limited amounts of bonds that an individual can buy per year; besides that they have a low principal risk and a guaranteed return on the investment. If individuals were planning for their own future, then a Non-Marketable Security will be a good option.